<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			#box{
				width: 50px;
				height: 50px;
				margin: 0 auto;
				background: yellow;
			}
		</style>
	</head>
	<body>
       <div id="box"></div>
       <script>
       	var box= document.getElementById("box");
        var a=0;
        box.onclick=function(){
            a++;
            if(a%2==0){
            	box.innerHTML="小";
            	box.style.width='50px';
                box.style.height='50px';
            }else{
            	box.innerHTML="大";
            	box.style.width='150px';
                box.style.height='150px';
            }
       	}
       </script>
	</body>
</html>
